Re: [crash, bisected] Re: clocksource: Resolve cpu hotplug deadlock with TSC unstable
From: Ingo Molnar
Date: Fri Sep 11 2009 - 03:38:05 EST
* Ingo Molnar <mingo@xxxxxxx> wrote:
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* Ingo Molnar <mingo@xxxxxxx> wrote:
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> * Jens Axboe <jens.axboe@xxxxxxxxxx> wrote:
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> > I went to try -tip btw, but it crashes on boot. Here's the
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> > backtrace, typed manually, it's crashing in
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> > queue_work_on+0x28/0x60.
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> >
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> > Call Trace:
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> > queue_work
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> > schedule_work
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> > clocksource_mark_unstable
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> > mark_tsc_unstable
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> > check_tsc_sync_source
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> > native_cpu_up
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> > relay_hotcpu_callback
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> > do_forK_idle
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> > _cpu_up
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> > cpu_up
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> > kernel_init
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> > kernel_thread_helper
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> hm, that looks like an old bug i fixed days ago via:
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> 00a3273: Revert "x86: Make tsc=reliable override boot time stability checks"
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> Have you tested tip:master - do you still know which sha1?
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Ok, i reproduced it on a testbox and bisected it, the crash is
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caused by:
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7285dd7fd375763bfb8ab1ac9cf3f1206f503c16 is first bad commit
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commit 7285dd7fd375763bfb8ab1ac9cf3f1206f503c16
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Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
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Date: Fri Aug 28 20:25:24 2009 +0200
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clocksource: Resolve cpu hotplug dead lock with TSC unstable
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Martin Schwidefsky analyzed it:
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I've reverted it in tip/master for now.
and that uncovers the circular locking bug that this commit was
supposed to fix ...
Martin?
Ingo
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